Thomas Cullen

Sharks as apex predators in the Late Cretaceous Western Interior Seaway empirically revealed by zinc isotope analyses Food web structures and trophic interactions among Late Cretaceous marine taxa remain largely ambiguous due to the challenges in reconstructing ecolog…

www.sciencedirect.com/science/arti...

Lead by Jeremy McCormack of @goetheuni.bsky.social, and with a miniscule contribution from me, we present geochemical evidence that sharks were marine apex predators since at least the Late Cretaceous. 🐟🦈🧪 #paleobiology #geochemistry

A round colourless brilliant cut gem reflecting lots of colours sits on a frosted plinth with the number 45 on it. It sits in front of a grey background. At the Royal Ontario Museum.

Another Guess the Gem!! What mineral do you think this gem is? Hint: this mineral is commonly used for the age dating of rocks. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Acceleration hotspots of North American birds’ decline are associated with agriculture Human activities might have accelerated declines of population abundance, but this acceleration remains underexplored. Using 1033 North American Breeding Bird Survey routes, we analyze abundance chang...

Thrilled to share our new paper out in @science.org, led by François Leroy and Petr Keil! Using the Breeding Bird Survey, we document not only a continent-wide decline in bird abundance since the 1980s — but, crucially, the acceleration of these declines over time. www.science.org/doi/10.1126/...

Interbreeding between Neanderthals and modern humans was strongly sex biased Sex biases in admixture and other demographic processes are recurrent features throughout human evolution. For admixture between Neanderthals and anatomically modern humans (AMHs), sex bias has been p...

www.science.org/doi/10.1126/...

Argentine fossil rewrites evolutionary history of a baffling dinosaur clade - Nature A skeleton of the alvarezsauroid Alnashetri cerropoliciensis—representing a highly complete alvarezsauroid skeleton from South America—provides evidence on the evolution of the peculiar anatomy and mi...

Makovicky, P.J., Mitchell, J.S., Meso, J.G. et al. Argentine fossil rewrites evolutionary history of a baffling dinosaur clade. Nature (2026). doi.org/10.1038/s415...

Two clear gems, the one to the left is very large and oval on a small round white plinth, to the right is a rectangular gem. They sit on a glass shelf with a white 8 on it in front of a black background. At the Denver Museum of Nature and Science.

Guess the Gem time!! What mineral do you think these gems are? Hint: it’s very abundant on earth. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

While >70% of bone strength variation is explained by structure, a new manuscript by Skedros et al shows that collagen fiber orientation (CFO) in deer calcanei also reflects compression vs. tension loading. anatomypubs.onlinelibrary.wiley.com/doi/10.1002/...

this could be the greatest goal call in hockey history

Oxygen Isotopes in Tree Rings Track Neotropical Climate Dynamics Tree-ring δ18O from Abies guatemalensis in Central America captures interannual variations in boreal summer rainfall Lighter δ18O years are associated with a weakening of the Caribbean Low-Level ...

Excited to have this paper out showing a strong coupling between Central American tree-ring oxygen isotopes and ocean–atmosphere dynamics (interbasin SST gradients, ITCZ, CLLJ... ). Many thanks to all co-authors!

agupubs.onlinelibrary.wiley.com/doi/10.1029/...

The collapse of curiosity driven research has occurred in STEM too. Everything has to be outcomes focused - cure disease, grow better crops, etc. But so much of what humanity has discovered is from "basic" curiosity-driven science. I'm hugely in favor of funding curiosity in every discipline.

Specimen of labradorite that shows patches of bright blue, yellow green, and brown on the front surface. The sides are grey. It sits on a grey plinth on a grey background. A small frosted plastic label says Anorthite Anorthite on the lower left. At the Royal Ontario Museum.

Gorgeous technicolour labradorite!! This labradorescence shows a range of colours across the labradorite, a variety of feldspar that is primarily the mineral anorthite. #MineralMonday #GeoscienceBluesky ⚒️🧪

The billion-dollar case for sustaining palaeontology’s digital databases - Nature Ecology & Evolution The authors survey community palaeontological databases, documenting their contributions to science as well as their vulnerabilities, and provide recommendations for the future of open science databas...

Dowding, E.M., Dunne, E.M., Collins, K.S. et al. The billion-dollar case for sustaining palaeontology’s digital databases. Nat Ecol Evol (2026). doi.org/10.1038/s415...

The entirety of a mounted Patagotitan mayorum in a hall under purple lights showing its long neck and tail. At the Natural History Museum in London.

The absolutely massive Patagotitan mayorum!! This sauropod is one of the largest known titanosaur species. It would have been amazing to see something so massive walking around. #FossilFriday ⚒️🧪

Crevasse in a whitish rock with yellow crystals of gaidonnayite and milky natrolite on a black background. At the Museum of Nature.

To celebrate this year’s International Day of Women and Girls in Science, here is gaidonnayite, named after Dr Gabrielle Donnay, nestled in with some natrolite.
She has two minerals named after her!! Two of the very few minerals discovered in Canada named after a woman. #WomenInSTEM #IDWGS ⚒️🧪

Pinecone made up of sulphur, so it’s a pale brown colour. It sits on a clear plexiglass plinth on a white background. At the Field Museum.

SO COOL!! Sulphur taking the shape of a pinecone!! It replaced the original material. #MineralMonday #GeoscienceBluesky ⚒️🧪

RVC will be advertising 2 new faculty posts soon, broadly in comparative biomedical science (our department name). Email me jhutchinson@rvc.ac.uk to get informed (I am not on the search panel; just helping). www.rvc.ac.uk/about/the-rv...

Is the Fundamental Theorem of Natural Selection of any use? Abstract. There have been many recent discussions of the Fundamental Theorem of Natural Selection, with an emphasis on its mathematical accuracy. It is arg

"There is still life in the old dog."

Brian Charlesworth on Fisher's Fundamental Theorem in @journal-evo.bsky.social

doi.org/10.1093/evol...

Our paper on the mysterious Devonian organism Prototaxites has now finally been published! See the paper here (www.science.org/doi/10.1126/...) and our explainer thread below!
Prototaxites reconstruction by Matt Humpage

Investigating size-asymmetric feeding among tyrannosaurids using tooth marks on a metatarsal from the Judith River Formation, Montana, USA The Judith River Formation in Montana, USA, is a key Campanian-aged sedimentary package, with a rich fossil assemblage, including multiple tyrannosaur…

Read the paper here, FREE:

Nielsen J; Fowler DW; Wyenberg-Henzler, T; Jacobsen AR, & Pearce, C. (2026) Investigating size-asymmetric feeding among tyrannosaurids using tooth marks on a metatarsal from the Judith River Formation, Montana, USA. Evolving Earth

www.sciencedirect.com/science/arti...

Close up of a side of a specimen consisting of clear to white quartz, pyrrhotite, and other minerals with deep green crystals of uvarovite speckled throughout. It sits on a black background. At the Hunterian.

Look at these gorgeous deep green crystals of uvarovite, some showing that classic garnet crystal shape!! It’s from Outokumpu, Finland. #MineralMonday #GeoscienceBluesky ⚒️🧪

A very large pale blue cut gem in the shape of a rounded rectangle on display on a white plinth on a white background. At the Natural History Museum in London.

Guess the Gem!! What mineral do you think this gem is? Hint: at 2,982 carats, it’s the largest cut gem in this museum’s collection! #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Mounted Unenlagia comahuensis made up of whitish bones crouched forward on a wooden plinth and the back of a large black mounted dinosaur behind it. At the Museum national d’Histoire naturelle.

Therapod dinosaur Unenlagia comahuensis ready to pounce. #FossilFriday ⚒️🧪🦖

Writing is thinking

Outsourcing the entire task of writing to LLMs will deprive us of the essential creative task of interpreting our findings and generating a deeper theoretical understanding of the world.

Quantifying the unrecorded loss of avian phylogenetic diversity Humans have drastically reduced avian diversity, with the majority of extinctions occurring on islands. Previous studies have quantified various aspects of this decline, including both taxonomic and ...

🚨 New paper out in @ecography.bsky.social ! 📝

Led by Dr. Søren Faurby, we built upon the estimated unrecorded bird extinctions by @r-cooke.bsky.social et al. 2023 and try to estimate the corresponding unrecorded loss of phylogenetic diversity. 🦤🧬

Check the full paper here:
doi.org/10.1002/ecog...

An oval cabochon that sits on a small frosted plexiglass plinth on a grey background. The number 20 is on the plinth. At the Royal Ontario Museum.

Guess the Gem today!! What mineral or variety do you think this gem is? Hint: it has a schiller. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎

Prairie wetland drainage is increasing Canada’s carbon footprint: study REGINA — A new study published in the international science journal FACETS shows that draining small agricultural Prairie wetlands is adding significantly to Canada’s greenhouse gas emissions, with a cost that researchers say has been large...

FACETS in the news!

Draining Prairie wetlands is quietly driving up Canada’s greenhouse gas emissions. A new FACETS study shows wetland loss boosts agricultural emissions by at least 5%—a major blind spot in national climate accounting. 🌾 Read the news article by #620CKRM: https://ow.ly/PX7S50XVM2U

Big block specimen with its front face showing bright pink interspersed with some white crystals, with an outside brown weathered surfaces. It resembles a fatty steak. Some specimens sit in front of rose quartz, rhodonite, and fluorite. At the Great Northern Museum: Hancock.

So this one is bacon adjacent, it looks like wagyu beef 😂. This is the pink variety thulite of the mineral zoisite from Norway. #MineralMonday #GeoscienceBluesky ⚒️🧪

A shake-up of the dinosaur family tree! Rhabdodontids are not ornithopods. They are ceratopsians.

There were horned dinosaurs in Europe! As shown by a new fossil of Ajkaceratops from Hungary!

Check out our new study, led by @tweetisaurus.bsky.social ⤵️

A hidden diversity of ceratopsian dinosaurs in Late Cretaceous Europe - Nature New results indicate that rhabdodontids and the previously described Ajkaceratops are actually distinctive European ceratopsians, a group better known from Asia and North America.

Out in @nature.com today, we shake up the ornithischian family tree. Remember those weird Late Cretaceous iguanodontians, the rhabdodontids? Well they're weird because they aren't iguanodontians. They're ceratopsians. Well, at least some of them are... www.nature.com/articles/s41...

A rounded rectangular cut bright pink gem in a clear plastic gem case on cream foam. It sits on a cream background. At the National Museum of Ireland.

Guess the Gem Tuesday!! What mineral do you think this gem is? Hint: the mineral’s crystals are barrel shaped. #GuessTheGem #GeoscienceBluesky ⚒️🧪💎